Delivery of solid chemical precursors

ABSTRACT

Systems and methods are provided for delivering solid precursors in deposition processes. A flow monitor is used to measure and regulate the flow of vaporized solid precursor material from a vaporization chamber to a deposition chamber. The flow monitor chokes the supply of vapor into deposition chamber to regulate vapor flow. To avoid condensation of the solid precursor material in the delivery lines or flow monitor, a controller is placed in a feed back loop to monitor the flow rate make adjustments to the amount of vapor available at the inlet of the flow monitor.

BACKGROUND OF THE INVENTION

The present invention relates in general to vapor delivery systems fordeposition processes, and in particular to systems and methods forreliably delivering solid precursors to a deposition chamber.

Chemical vapor deposition (CVD) is a common process used in themanufacturing of films, coatings, and semiconductor devices. In a CVDprocess, a layer is formed on a substrate such as a semiconductor waferby the reaction of vapor phase chemicals on or near the surface of thesubstrate. CVD processing is highly desirable in many applications dueto it's relatively fast processing times and ability to form highlyconformal layers on irregular shaped surfaces including deep contactopenings.

CVD processes typically deliver one or more gaseous reactants to thesurface of substrates positioned within a deposition chamber undertemperature and pressure conditions favorable to the desired chemicalreactions. As such, the types of layers that can be formed on asubstrate using CVD techniques is limited by the types of reactants orprecursors that can be delivered to the surface of the substrate.

Liquid precursors are commonly used in CVD processes due to the ease oftheir delivery to the deposition chamber. In typical liquid precursorsystems, the liquid precursor is placed in a bubbler and heatedsufficiently to transform the precursor to the vapor phase. A carriergas typically either travels through the liquid precursor or passes overthe bubbler at a controlled rate thus saturating the carrier gas withthe precursor. The carrier gas then carries the liquid precursor to thesurface of the substrate. Liquid precursors are commonly employed in CVDprocesses because the amount of liquid precursor can be precisely andconsistently controlled.

The techniques developed for the delivery of liquid precursors cannot beused to reliably deliver solid precursors however. It is difficult tovaporize a solid precursor at a controlled rate such that reproducibleflows are achieved. As a solid precursor sublimates, the shape andmorphology of the remaining solid precursor changes. The changing volumeof the solid precursor results in a continuously changing rate ofvaporization. The changing rate of vaporization is notable particularlyin thermally sensitive compounds. Additionally, an oversupply ofvaporized solid precursor can result in condensation of the vapor backinto a solid thus clogging vapor delivery lines and other monitoringequipment. Further, the use of a carrier gas is substantiallyineffective as a means to implement rapid changes to the flow of thesolid precursors.

Despite the difficulties in delivering solid precursors in CVDprocesses, there are many desirable precursor materials including forexample, organometallic precursors, that are readily available in solidform. Further, many desirable precursor materials including organic andinorganic precursor materials may not be readily available in gas orliquid form. Also, solid precursors are particularly useful in thedeposition of metal-based films, such as metal nitrides and metalsilicides.

Therefore, there is a need in the art for a vapor delivery system fordelivering solid precursors in a CVD process at a controllable rate.

SUMMARY OF THE INVENTION

This need is met by the present invention wherein systems and methodsare provided for delivering solid precursors in deposition processes. Aflow monitor is used to measure the flow of vaporized solid precursormaterial. The flow monitor is capable of measuring vapor flow that ismaintained at a high temperature and low inlet and outlet pressure toavoid condensation of the precursor. The vapor flow measured by the flowmonitor is fed back to a controller arranged to adjust the supply ofvapor at the inlet of the flow monitor.

In accordance with one embodiment of the present invention, a solidprecursor material is sublimated in a vaporization chamber by heatingthe solid precursor material with a fast response heater. As thevaporized solid precursor material is fed from the vaporization chamberinto a deposition chamber, a flow monitor measures the vapor flow. Thevapor flow measurements are input into a controller that communicateswith the fast response heater to effect rapid changes to the temperatureapplied to the solid precursor material. As such, the temperaturechanges affect the rate at which the solid precursor sublimates, andthus the vapor flow is controlled.

In accordance with another embodiment of the present invention, a solidprecursor material is sublimated in a vaporization chamber and fed intoa deposition chamber. As the vaporized solid precursor material is fedinto the deposition chamber, a flow monitor measures the vapor flow. Thevapor flow measurements are input into a controller that communicateswith a valve positioned upstream of the flow monitor to adjust theamount of excess vapor siphoned by the valve, and thus the vapor flow iscontrolled.

In accordance with another embodiment of the present invention, a solidprecursor material is sublimated in a vaporization chamber by heatingthe solid precursor material with a fast response heater. As thevaporized solid precursor material is fed from the vaporization chamberinto a deposition chamber, a flow monitor measures the vapor flow. Thevapor flow measurements are input into a controller that communicateswith the fast response heater to effect rapid changes to the temperatureapplied to the solid precursor material and/or the controllercommunicates with a valve positioned upstream of the flow monitor toadjust the amount of excess vapor siphoned by the valve, and thus thevapor flow is controlled.

Accordingly, it is an object of the present invention to provide systemsand methods of delivering a solid precursor to a deposition process.

It is an object of the present invention to provide systems and methodsto reliably measure the vapor flow of a solid precursor.

It is an object of the present invention to provide systems and methodsto reliably and rapidly change the flow of vapor supplied to adeposition process.

Other objects of the present invention will be apparent in light of thedescription of the invention embodied herein.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of the preferred embodiments of thepresent invention can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals, and in which:

FIG. 1 is a schematic illustration of a vapor delivery system for adeposition process according to one embodiment of the present invention;

FIG. 2 is a flow chart illustrating a simplified controller scheme;

FIG. 3 is a schematic illustration of the vapor delivery system of FIG.1, further illustrating multiple controller inputs and the use of apressure regulator;

FIG. 4 is a flow chart illustrating a simplified controller schemeincorporating a check to determine whether vapor is within a pressureguard band;

FIG. 5 is a schematic illustration of the vapor delivery system of FIG.1, further illustrating an external pressure sensor positioned along thedelivery line upstream of a flow monitor;

FIG. 6 is a schematic illustration of a vapor delivery system fordeposition processing according to another embodiment of the presentinvention;

FIG. 7 is a schematic illustration of the vapor delivery system of FIG.4, further illustrating the use of a pressure regulator; and,

FIG. 8 is a schematic illustration of a vapor delivery system fordeposition processing according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration, and not by way oflimitation, specific preferred embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand that logical, mechanical and electrical changes may be made withoutdeparting from the spirit and scope of the present invention.

Referring to FIG. 1, a vapor delivery system 100 for the controlleddelivery of solid precursors is illustrated. A vaporization chamber 102includes a housing 104 and a first surface 106 that is coupled to aheating device 108. The heating device 108 regulates the temperature ofthe first surface 106 and includes a variable temperature control 110 toadjust the temperature that the heating device 108 supplies to the firstsurface 106. The temperature control 110 is arranged to vary thetemperature of the heating device 108 over a range of temperatures asmore fully explained herein.

During deposition processing, a solid precursor material 112 ispositioned on the first surface 106 of the vaporization chamber 102, andthe heating device 108 heats the first surface 106 to a temperaturesufficient to transform the solid precursor material 112 to a vapor 114.As such, at least a portion of the temperatures within the range oftemperatures controllable by the temperature control 110 are sufficientto sublimate or otherwise transform the solid precursor material 112 toa vapor 114.

The heating device 108 does not need to be in direct contact with thefirst surface 106. Rather, it will be understood that any coupling canbe used to transfer the energy generated by the heating device 108 toheat the first surface 106. The exact relationship between the heatingdevice 108 and the first surface 106 will depend upon such factorsincluding the construction of the vaporization chamber 102, the type ofheating device 108 used, and the intended solid precursor material 112.For example, the heating device 108 may comprise a fast response heatersuch as a thermoelectric heater that is based upon the thermoelectric(Peltier) effect. The temperature control 110 can be implemented as anydevice that adjusts the temperature output by the heating device 108.For example, the temperature control 110 may comprise an analog switch,circuit, a PID temperature controller or other digital circuit.

As a solid precursor material 112 sublimates, the shape and morphologyof the remaining solid precursor material 112 changes. The changingvolume of the solid precursor results in a continuously changing rate ofvaporization. As such, the heating device 108 is preferably capable ofregulating the temperature of the first surface 106 over a wide range oftemperatures, room temperature to 400 degrees Celsius for example.Further, the heating device 108 should be capable of rapid temperaturechange. For example, a change of 20-30 degrees within milliseconds ispreferable. The present invention is in no way limited by the rate inwhich the heating device 108 can change temperatures, however, asexplained more fully herein, results of controlling vapor flow may varydepending upon the ability of the heating device 108 to changetemperature.

The vapor 114 travels out the vaporization chamber 102 and into adelivery line 116. The delivery line 116 comprises any tubing or conduitsuitable for routing the vapor 114. A flow monitor 118 is positionedalong the delivery line 116 in such a manner as to be able to measurethe vapor flow therethrough. As illustrated, the flow monitor 118 ispositioned inline with the delivery line 116 such that a first deliveryline section 120 routes the vapor 114 from the vaporization chamber 102to the flow monitor 118, and a second delivery line section 122 routesthe vapor 114 from the flow monitor 118 to a deposition chamber 124.

The vapor 114 flows through the deposition chamber 124 and onto one ormore substrates, wafers, or other surfaces 126. Residual vapor is drawnfrom the deposition chamber 124 through the exhaust port 128 by the pump130. The deposition chamber 124 is also sometimes referred to as aprocess chamber, reactor chamber, or deposition reactor. It will beappreciated that the vapor delivery system 100 of the present inventioncan be configured to supply vaporized solid precursors to any depositionchamber 124 for material deposition performed using established CVD orany other deposition processes as are known in the art.

The flow monitor 118 comprises a device capable of accurately measuringthe vapor flow therethrough. The flow monitor 118 must be capable ofgenerating accurate flow measurements at both high temperatures and lowinlet and outlet pressures with minimal and preferably no restriction tothe vapor flow. The high temperatures and low pressures are required tomaintain the solid precursor material 112 in the vapor phase. Asillustrated, the flow monitor 118 comprises an inlet 132, an outlet 134,a flow sensor 136, and associated electronics 140. The flow monitor 118may also optionally include therein, a flow restrictor 138, a pressuresensor 142, a temperature sensor 144, or both. The electronics 140provides the ability to output the measured flow, and optionaltemperature and pressure measurements. The electronics 140 may alsoperform calculations or processes required by the flow monitor 118.

The flow monitor 118 may be implemented for example, as either an analogor digital mass flow controller. However, a digital mass flow controllerbased upon either pulsed gate flow or sonic nozzle technologies arepreferred due to the accuracy and control afforded by such devices. Itwill be appreciated that the flow monitor 118 may require additionalhardware depending upon its implementation. For example, a thermal massflow controller gas stick may require additional components such aspressure transducers, filters, bypass valves, and in some cases,pressure regulators (not shown). Further, some mass flow controllersdetermine vapor flow based upon a measured pressure. As such, onepressure sensor and the appropriate electronics can output both thevapor flow and pressure. Accordingly, one physical sensor or device canembody one or more of the sensors schematically illustrated herein.

The flow monitor 118 is capable of controlling the flow rate into thedeposition chamber 124. By controlling the flow rate into the depositionchamber 124, the deposition rate of the solid precursor material 112onto the surface of the substrate 126 positioned within the depositionchamber 124 is controlled. The flow monitor 118 controls the flow rateof the vapor 114 into the deposition chamber 124 by choking the flow ofvapor in the first delivery line section 120 to let the desired amountof flow through. This is accomplished for example, by closing the flowrestrictor 138 within the flow monitor 118. However, as the flow ischoked off, the pressure upstream of the flow restrictor 138 increases.Should the pressure rise too much, condensation will occur as thevaporized solid precursor material 112 transforms back into the solidphase. If the solid precursor material 112 transforms from the vaporphase back to the solid phase, the flow monitor 118 and first deliveryline section 120 can clog, jam, or otherwise suffer performancedegradation.

To maintain the solid precursor material 112 in the vapor phase, acontroller 146 is used to adjust the temperature of the heating device108 to account for detected or expected changes in pressure. Thecontroller 146 has a first input 148 coupled to the flow monitor 118.The first input 148 receives as an input, the vapor flow measured by theflow monitor 118. The controller 146 further includes a first output 150coupled to the temperature control 110 of the heating device 108. Thefirst output 150 is arranged to adjust the temperature generated by theheating device 108 in such a manner to control the flow of vapor 114through the vapor delivery system 100. By reducing the flow of vapor114, the pressure in the first delivery line section 120 is alsoreduced.

It will be appreciated that the controller 146 can be implemented in anumber of ways. For example, the controller 146 may be implemented asdedicated hardware, as a microprocessor based circuit, as a dedicatedturnkey computer system, or a general-purpose computer running theappropriate software to implement the present invention.

Referring now to FIG. 2, a controller scheme 200 is illustrated. Themeasured vapor flow is read in block 202. The measured vapor flow isthen compared to a desired vapor flow in block 204. In decision block206, the measured vapor flow is tested to determine whether the measuredvapor flow is at too low a rate for the given deposition process. If themeasured flow rate is too low, the flow rate is increased in block 208,and a new measurement is taken by feeding back control to block 202. Ifthe measured flow is not too low, the measured flow is tested todetermine whether it is too high in block 210. If the measured flow istoo high, the flow rate is reduced or choked in block 212 and a newmeasurement is taken by feeding back control to block 202. Otherwise,the flow rate is acceptable, and control is fed back to block 202 totake a new measurement. It will be understood that this flow chart isonly representative of the possible implementations of the inventionmore fully described herein. Further, the desired flow may actually berepresented as a range of acceptable flows.

Referring back to FIG. 1 with reference to FIG. 2, for a given solidprecursor material 112, the controller 146 (such as a general purposecomputer) has preprogrammed therein, a desired flow rate or range ofacceptable flow rates to achieve a desired deposition layer. When thedeposition process begins, the controller 146 reads the measured flowand compares the measured flow to the desired flow rate. If the measuredvapor flow is too low, the controller 146 adjusts the temperature of thefirst surface 106 of the vaporization chamber 102 by sending a controlsignal to the temperature control 110 of the heating device 108 toaffect the necessary adjustment, for example, to increase thetemperature of the first surface 106. If the measured flow exceeds thedesired flow, the output of the controller 146 signals the temperaturecontrol 110 to reduce the temperature applied to the first surface 106of the vaporization chamber 102 thus lowering the quantity of solidprecursor material 112 that vaporizes and thus reduces the vapor flow.It will be appreciated that the amount of a particular adjustment willdepend upon the type of solid precursor, the response time of theheating device 108 used, the reaction time of the flow monitor 118 todetermine the vapor flow rate, and other factors. Further, the desiredflow rate may have different values during various portions of thedeposition process. The system continues to monitor the vapor flowthrough the flow monitor 118 and make adjustments as necessary until thedeposition process is complete.

The vapor delivery system 100 optionally includes pressure regulation toassist in maintaining the solid precursor material 112 in the vaporphase. There are a number of ways to accomplish pressure regulation.According to one embodiment of the present invention, an inert gas isfed into the delivery line 116 as illustrated in FIG. 3. The inert gas152 is provided by a gas source 154 and is fed into the vaporizationchamber 102 through a gas line 156. A flow regulator 158 is provided tocontrol the amount of inert gas 152 that enters the vaporization chamber102. The controller 146 optionally comprises a second output 160 thatcouples to the flow regulator to adjust the amount of inert gas 152 thatis introduced during deposition processing.

It will be observed that any number of optional flow monitors 162 andvalves 164 may be positioned inline with the gas line 156 beforeentering the inlet of the vaporization chamber 102. Further, whileschematically, the second output 160 of the controller 146 isillustrated as being coupled to the flow regulator 158, it will beunderstood that other control schemes may be implemented. For example,if an optional flow monitor 162, such as a digitally controlled massflow controller is positioned inline with the gas line, the secondoutput 160 of the controller 146 may couple to the mass flow controllerto regulate the amount of inert gas 152 that enters the vaporizationchamber 102 and delivery line 116.

Additionally, depending upon the selection of solid precursor material112, an optional carrier gas 166 may be used to assist the vapor 114 intransmitting from the vaporization chamber 102 to the deposition chamber124. It will be appreciated that the carrier gas 166 is supplied by thecarrier gas source 167 and may utilize a second gas line 168, flowregulator 170, flow monitor 172, and other components as is known in theart. The carrier gas 166 may be fed into the vaporization chamber 102using a second inlet (not shown), or alternatively, the carrier gas 166may tie into the inert gas line 156 downstream from the inert gas flowregulator 158.

If the flow monitor 118 includes the optional pressure sensor 142 and iscapable of generating an output signal representing the measuredpressure, this signal may be fed into the controller 146 as a secondinput 174. Likewise, if the flow monitor 118 includes the optionaltemperature sensor 144 and is capable of generating an output signalrepresenting the measured temperature, this signal may be fed into thecontroller 146 as a third input 176.

The addition of measured pressure and temperature data allows for moresophisticated processing by the controller 146. For example, thecontroller 146 contains predetermined data that provides the temperatureand pressure conditions required to maintain a particular solidprecursor in the vapor phase. This information may be stored forexample, in the form of a formula or lookup table. Based upon giventemperature conditions, a guard band, or range of acceptable pressuresis determined. The guard band will vary depending upon the type of solidprecursor being sublimated for deposition processing. The controller 146can now monitor both the flow rate to ensure proper depositionprocessing, and make sure the pressure is maintained within the guardband to avoid condensation from forming in the flow monitor 118 anddelivery line 116.

Referring now to FIG. 4, a controller scheme 300 including pressureguard band testing is illustrated. The measured vapor flow is read inblock 302. The measured vapor flow is then compared to a desired vaporflow in block 304. In decision block 306, the measured vapor flow istested to determine whether the measured vapor flow is at too low a ratefor the given deposition process. If the measured flow rate is too low,the flow rate is increased in block 308, and a new measurement is takenby feeding back control to block 302. If the measured flow is not toolow, the measured flow is tested to determine whether it is too high inblock 310. If the measured flow is not too high, then control is fedback to block 302 and a new flow measurement is taken. If the measuredflow is too high, the flow rate is reduced or choked in block 312. Themeasured pressure is checked against the pressure guard band in block314 if the measured pressure is within the guard band, a new flowmeasurement is taken by feeding back control to block 302. If themeasured pressure is outside the guard band, the pressure is reduced inblock 316. It will be understood that this flow chart is onlyrepresentative of the possible implementations of the invention morefully described herein. Further, the desired flow may actually berepresented as a range of acceptable flows.

Referring back to FIG. 3, it will be appreciated that the temperatureinput can also come from the heating device 108. For example, theheating device 108 may have a temperature output that couples to thethird input 176 of the controller 146. Under such an arrangement, thetemperature sensor 144 in the flow monitor 118 is not required. It willbe appreciated that numerous factors affect the decision to use aseparate temperature sensor or whether the heating device 108 cangenerate sufficient temperature measurements including for example, thelength of the first delivery line section 120 and the type of outputsavailable on the heating device 108.

The optional temperature and pressure sensors 142, 144 need notphysically reside within the flow monitor 118. Referring to FIG. 5, theflow monitor 118 does not include a built in pressure sensor. Rather, apressure sensor 178 is provided in line with the delivery line 116. Itis preferable to locate the pressure sensor 178 proximate to, andupstream from the flow monitor 118, however, the pressure sensor 178 mayalso be positioned downstream of the flow monitor 118. Further, thepressure sensor 178 may be positioned in any desired position along thedelivery line 116. It will be appreciated that a temperature sensor mayalso be positioned along the delivery line 116 (not shown) in a similarfashion as that described for the pressure sensor 178.

Referring to FIG. 6, a vapor delivery system according to anotherembodiment of the present invention is illustrated. As pointed outabove, the flow monitor 118 controls the flow rate of the vapor 114 intothe deposition chamber 124 through the second delivery line section 122by choking the flow of vapor in the first delivery line section 120 tolet the desired amount of flow through. However, as the vapor flow ischoked off, pressure upstream of the flow monitor 118 increases. Whereasan embodiment of the present invention discussed above with reference toFIGS. 1-5 offsets the increased pressure during choked off periods byadjusting the temperature of the heating device 108, the embodimentillustrated in FIG. 6 offsets the increased pressure by bleeding offexcess vapor 114.

The delivery line 116 further includes a third delivery line section 180that couples to the first delivery line section 120 upstream of the flowmonitor 118. A valve 182 is positioned inline with the third deliveryline section 180, and a pump 184 is provided to draw vapor 114 in thedirection of the third delivery line section 180. The valve 182 can beany implemented with any number of valve arrangements, including a massflow controller. For example, the valve 182 may comprise a pulsed gateflow or sonic nozzle mass flow controller 146. Digital valves and pulsedgate flow devices are preferred over analog counterparts due to the fastresponse time and control typically afforded by such devices.

The controller 186 includes a first output 188 coupled to the valve 182,and the logic in the controller 186 is configured to adjust the valve182 to selectively bleed off vapor 114 in the first delivery linesection 120 by siphoning excess vapor 114 through the third deliveryline section 180. That is, the measured vapor flow is compared to apredetermined vapor flow. If the measured vapor flow exceeds the desiredvapor flow, any excess vapor is bled of by opening the valve 182 to drawa portion of the vapor 114 into the third delivery line section 180 andaway from the flow monitor 118. The controller 186 inputs and variationsthereof are similar to those described more fully herein with referenceto FIGS. 1-5.

The heating device 108 is schematically illustrated as having a variabletemperature control 110 because the temperature applied to the firstsurface 106 may require adjustment when switching from one solidprecursor material 112 to the next. However, in this embodiment, it isnot required that the heating device 108 be a fast response heater.

FIG. 7 illustrates the embodiment as illustrated in FIG. 6 with theaddition of optional pressure regulation to assist in maintaining thesolid precursor material 112 in the vapor phase. Similar to the pressuresystem discussed with reference to FIG. 3, the inert gas 152 is providedby the gas source 154 and is fed into the vaporization chamber 102through the gas line 156. A flow regulator 158 is provided to controlthe amount of inert gas 152 that enters the vaporization chamber 102.The controller 186 optionally comprises a second output 190 that couplesto the flow regulator 158 to adjust the amount of inert gas 152 that isintroduced during deposition processing. Further, depending upon theselection of solid precursor material 112, an optional carrier gas 166may be used to assist the vapor 114 in transmitting from thevaporization chamber 102 to the deposition chamber 124. The carrier gas166 is provided by a carrier gas source 167, and is fed into thevaporization chamber 102 using a second gas line 168, flow regulator170, and other components separate from the inert gas source 154. FIG. 7also illustrates the use first, second and third controller inputs 148,174, and 176 from the flow sensor 136, pressure sensor 142, andtemperature sensor 144 respectively. As previously described herein, thepressure and temperature sensors 142, 144 are optional.

FIG. 8 illustrates another embodiment of the present invention. Thevapor delivery system is similar to that described with reference toFIGS. 6-7, and further includes a third output 192 that feeds backcontrol from the controller 186 to the temperature control 110 of theheating device 108. This structure allows a high degree of flexibilityin the implementation of the controller 186. For example, according toone embodiment of the present invention, the controller 186 isconfigured to adjust the temperature of the first surface 106 whencoarse adjustments are required to the vapor flow. The controller 186 isconfigured to regulate the valve 182 when fine adjustments are required.It will be appreciated that depending upon such factors as the abilityof the pump 184 to create a vacuum and the length of the third deliveryline section 180, the opening and closing the valve 182 can result infaster response times than regulating the heating device 108.

According to another embodiment of the present invention, the controller186 is arranged to regulate the valve 182 and adjust the temperatureapplied to the first surface 106 by adjusting the temperature control110 generally at the same time. Alternatively, the controller 186adjusts vapor flow by adjusting the third output 192 to change thetemperature of the heating device 108, and thus affecting vapor flow,and adjusting the first and second outputs 188, 190 to adjust formeasured pressure.

While illustrated having a pressure sensor 178 and a flow sensor 118that includes a built in temperature sensor 144, it will be appreciatedthat the inputs to the controller 186 can include any of theconfigurations discussed above with reference to FIGS. 1-7.

Although the invention described above with reference to FIGS. 1-8 areillustrated with a single vaporization chamber 102 and a single solidprecursor material 112, it will be appreciated that any number ofvaporization chambers 102 may feed into a single deposition chamber 124using the techniques, methods, and system described herein.

Further, any number of additional features of conventional vapordelivery systems may be used with the present invention as is known inthe art. For example, optional delivery line heaters may be used tomaintain the solid precursor in the vapor phase. The use of deliveryline heaters may be advantageous under conditions where excessive linelength is required to deliver the solid precursor.

Having described the invention in detail and by reference to preferredembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of theinvention defined in the appended claims.

What is claimed is:
 1. A vapor delivery system for a solid precursorcomprising: a vaporization chamber; a first surface within saidvaporization chamber, said first surface arranged to hold a solidprecursor material; a heating device having a temperature control, saidtemperature control arranged to vary the temperature of said heatingdevice over a range of temperatures, at least a portion of thetemperatures within said range of temperatures sufficient to transformsaid solid precursor material to a vapor, wherein said heating device isarranged to transfer heat to said first surface; a delivery line coupledto said vaporization chamber; a flow monitor arranged to measure theflow of said vapor through said delivery line; and, a controller havinga first input coupled to said flow monitor and a first output coupled tosaid temperature control of said heating device, said controllerarranged to control the supply of said vapor to said delivery line byvarying said first output to adjust the temperature of said heatingdevice based upon the measured flow of said vapor at said first input.2. A vapor delivery system for a solid precursor according to claim 1,wherein said heating device comprises a thermoelectric heating device.3. A vapor delivery system for a solid precursor according to claim 1,wherein said heating device is arranged to heat said first surface to atemperature sufficient to sublimate said solid precursor material.
 4. Avapor delivery system for a solid precursor according to claim 1,wherein said controller comprises a microprocessor based controller. 5.A vapor delivery system for a solid precursor according to claim 1,wherein said controller comprises a general purpose computer.
 6. A vapordelivery system for a solid precursor according to claim 1, wherein saidflow monitor comprises a pulsed gate flow mass flow controller.
 7. Avapor delivery system for a solid precursor according to claim 1,wherein said flow monitor comprises a sonic nozzle mass flow controller.8. A vapor delivery system for a solid precursor according to claim 1,further comprising a pressure sensor arranged to measure the pressure ofsaid vapor within said delivery line, wherein said controller has asecond input coupled to said pressure sensor, said second inputreceiving as a second input signal the measured pressure of said vapor.9. A vapor delivery system for a solid precursor according to claim 8,wherein said controller is arranged to vary said first output to adjustthe temperature of said heating device based upon the measured pressureof said pressure sensor.
 10. A vapor delivery system for a solidprecursor according to claim 9, wherein said controller is arranged tocompare said measured pressure against a guard band range of pressures,and said controller varies said first output to adjust the temperatureof said heating device if said measured pressure is outside of saidguard band range of pressures.
 11. A vapor delivery system for a solidprecursor according to claim 1, further comprising a temperature sensorarranged to measure the temperature of said vapor within said deliveryline, wherein said controller has a second input coupled to saidtemperature sensor, said second input receiving as a second input signalthe measured temperature of said vapor.
 12. A vapor delivery system fora solid precursor according to claim 1, further comprising a gas sourcecoupled to an inlet in said vaporization chamber, wherein said gassource is arranged to supply a gas to said delivery line, said gastransferred to said delivery line to regulate the pressure within saiddelivery line.
 13. A vapor delivery system for a solid precursoraccording to claim 12, wherein said controller further comprises asecond output adapted to adjust the amount of said gas that is suppliedto said delivery line by said gas source.
 14. A vapor delivery systemfor a solid precursor according to claim 12, wherein said gas comprisesan inert gas.
 15. A vapor delivery system for a solid precursorcomprising: a vaporization chamber; a first surface within saidvaporization chamber, said first surface arranged to hold a solidprecursor material; a heating device having a temperature control, saidtemperature control arranged to vary the temperature of said heatingdevice over a range of temperatures, at least a portion of thetemperatures within said range of temperatures sufficient to transformsaid solid precursor material to a vapor, wherein said heating device isarranged to transfer heat to said first surface; a delivery line coupledto said vaporization chamber; a flow monitor arranged to measure theflow of said vapor through said delivery line; a pressure sensorarranged to measure the pressure of said vapor within said deliveryline; a gas source coupled to an inlet in said vaporization chamber,said gas source arranged to supply an inert gas to said delivery line;and, a controller, said controller having: a first input coupled to saidflow monitor; a second input coupled to said pressure sensor; a firstoutput coupled to said temperature control of said heating device, and,a second output coupled to said gas source, wherein said controller isarranged to control the supply of said vapor to said delivery line byvarying said first output to adjust the temperature of said heatingdevice based upon the measured flow of said vapor at said first input,and by varying said second output to adjust the flow of said inert gasbased upon the measured pressure of said vapor at said second input. 16.A vapor delivery system for a solid precursor comprising: a vaporizationchamber; a first surface within said vaporization chamber, said firstsurface arranged to hold a solid precursor material; a heating devicehaving a temperature control, said temperature control arranged to varythe temperature of said heating device over a range of temperatures, atleast a portion of the temperatures within said range of temperaturessufficient to transform said solid precursor material to a vapor,wherein said heating device is arranged to transfer heat to said firstsurface; a delivery line coupled to said vaporization chamber; a flowmonitor arranged to measure the flow of said vapor through said deliveryline; a pressure sensor arranged to measure the pressure of said vaporwithin said delivery line; a temperature sensor arranged to measure thetemperature of said vapor within said delivery line; a gas sourcecoupled to an inlet in said vaporization chamber, said gas sourcearranged to supply an inert gas to said delivery line; a flow regulatorcoupled between said gas source and said inlet in said vaporizationchamber, and, a controller, said controller having: a first inputcoupled to said flow monitor; a second input coupled to said pressuresensor; a third input coupled to said temperature sensor; a first outputcoupled to said temperature control of said heating device, and, asecond output coupled to said flow regulator, wherein said controller isarranged to control the supply of said vapor to said delivery line byvarying said first output to adjust the temperature of said heatingdevice based upon the measured flow of said vapor at said first input,and by varying said second output to adjust the flow of said inert gasthrough said flow regulator, based upon the measured pressure of saidvapor at said second input, and the measured temperature of said vaporat said third input.
 17. A chemical vapor deposition system comprising:a vaporization chamber; a first surface within said vaporizationchamber, said first surface arranged to hold a solid precursor material;a heating device having a temperature control, said temperature controlarranged to vary the temperature of said heating device over a range oftemperatures, at least a portion of the temperatures within said rangeof temperatures sufficient to transform said solid precursor material toa vapor, wherein said heating device is arranged to transfer heat tosaid first surface; a deposition chamber; a delivery line arranged tocouple said vaporization chamber to said deposition chamber; a flowmonitor arranged to measure the flow of said vapor through said deliveryline; and, a controller having a first input coupled to said flowmonitor and a first output coupled to said temperature control of saidheating device, said controller arranged to control the supply of saidvapor to said delivery line by varying said first output to adjust thetemperature of said heating device based upon the measured flow of saidvapor at said first input.
 18. A vapor delivery system for a solidprecursor comprising: a vaporization chamber; a first surface withinsaid vaporization chamber, said first surface arranged to hold a solidprecursor material; a heating device arranged to heat said first surfacesufficient to transform said solid precursor material to a vapor; adelivery line coupled to said vaporization chamber, said delivery linearranged to route said vapor in a first direction and a seconddirection; a first flow monitor arranged to measure the flow of saidvapor through said delivery line in said first direction; a first valvearranged to regulate the flow of said vapor through said delivery linein said second direction; a first pump coupled to said delivery line,said first pump arranged to draw vapor through said delivery line insaid second direction; and, a controller having a first input coupled tosaid first flow monitor and a first output coupled to said first valve,said controller arranged to bleed off excess amounts of said vaporlocated in said first direction of said delivery line by varying saidfirst output to adjust said valve based upon the measured flow of saidvapor at said first input.
 19. A vapor delivery system for a solidprecursor according to claim 18, wherein said controller comprises amicroprocessor based controller.
 20. A vapor delivery system for a solidprecursor according to claim 18, wherein said controller comprises ageneral purpose computer.
 21. A vapor delivery system for a solidprecursor according to claim 18, wherein said first flow monitorcomprises a pulsed gate flow mass flow controller.
 22. A vapor deliverysystem for a solid precursor according to claim 18, wherein said firstflow monitor comprises a sonic nozzle mass flow controller.
 23. A vapordelivery system for a solid precursor according to claim 18, furthercomprising a pressure sensor arranged to measure the pressure of saidvapor within said delivery line in said first direction, wherein saidcontroller has a second input coupled to said pressure sensor, saidsecond input receiving as a second input signal the measured pressure ofsaid vapor.
 24. A vapor delivery system for a solid precursor accordingto claim 23, wherein said controller is arranged to vary said firstoutput to adjust said first valve based upon the measured pressure ofsaid pressure sensor.
 25. A vapor delivery system for a solid precursoraccording to claim 24, wherein said controller is arranged to comparesaid measured pressure against a guard band range of pressures, and saidcontroller varies said first output to adjust said first valve if saidmeasured pressure is outside of said guard band range of pressures. 26.A vapor delivery system for a solid precursor according to claim 18,further comprising a temperature sensor arranged to measure thetemperature of said vapor within said delivery line in said firstdirection, wherein said controller has a second input coupled to saidtemperature sensor, said second input receiving as a second input signalthe measured temperature of said vapor.
 27. A vapor delivery system fora solid precursor according to claim 18, further comprising a gas sourcecoupled to an inlet in said vaporization chamber, wherein said gassource is arranged to supply a gas to said delivery line, said gastransferred to said delivery line to regulate the pressure within saiddelivery line.
 28. A vapor delivery system for a solid precursoraccording to claim 27, wherein said controller further comprises asecond output coupled to said flow regulator, said second output adaptedto adjust the amount of said gas that is supplied to said delivery lineby said gas source.
 29. A vapor delivery system for a solid precursoraccording to claim 28, wherein said gas comprises an inert gas.
 30. Avapor delivery system for a solid precursor according to claim 18,wherein said first valve comprises a digital valve.
 31. A vapor deliverysystem for a solid precursor according to claim 18, wherein said firstvalve comprises a pulsed gate valve.
 32. A vapor delivery system for asolid precursor according to claim 18, wherein said first valve ispositioned upstream of said first flow monitor.
 33. A vapor deliverysystem for a solid precursor comprising: a vaporization chamber; a firstsurface within said vaporization chamber, said first surface arranged tohold a solid precursor material; a heating device arranged to heat saidfirst surface sufficient to transform said solid precursor material to avapor; a delivery line coupled to said vaporization chamber, saiddelivery line arranged to route said vapor in a first direction and asecond direction; a first flow monitor arranged to measure the flow ofsaid vapor through said delivery line in said first direction; a firstpressure sensor arranged to measure the pressure of said vapor withinsaid delivery line in said first direction; a first valve arranged toregulate the flow of said vapor through said delivery line in saidsecond direction; a first pump coupled to said delivery line, said firstpump arranged to draw vapor through said delivery line in said seconddirection; a gas source coupled to an inlet in said vaporizationchamber, said gas source arranged to supply an inert gas to saiddelivery line; a flow regulator between said gas source and said inletin said vaporization chamber; and, a controller having: a first inputcoupled to said first flow monitor; a second input coupled to said firstpressure sensor; a first output coupled to said first valve; and, asecond output coupled to said flow regulator; wherein said controller isarranged to bleed off excess amounts of said vapor in said firstdirection of said delivery line by varying said first output to adjustsaid valve and by varying said second output to adjust the amount ofsaid inert gas that is supplied to said delivery line by said gassource, based upon the measured flow of said vapor at said first inputand the measured pressure of said vapor at said second input.
 34. Avapor delivery system for a solid precursor comprising: a vaporizationchamber; a first surface within said vaporization chamber, said firstsurface arranged to hold a solid precursor material; a heating devicearranged to heat said first surface sufficient to transform said solidprecursor material to a vapor; a delivery line coupled to saidvaporization chamber, said delivery line arranged to route said vapor ina first direction and a second direction; a first flow monitor arrangedto measure the flow of said vapor through said delivery line in saidfirst direction; a first pressure sensor arranged to measure thepressure of said vapor within said delivery line in said firstdirection; a first temperature sensor arranged to measure thetemperature of said vapor within said delivery line in said firstdirection; a first valve arranged to regulate the flow of said vaporthrough said delivery line in said second direction; a first pumpcoupled to said delivery line, said first pump arranged to draw vaporthrough said delivery line in said second direction; a gas sourcecoupled to an inlet in said vaporization chamber, said gas sourcearranged to supply an inert gas to said delivery line; a flow regulatorbetween said gas source and said inlet in said vaporization chamber;and, a controller having: a first input coupled to said first flowmonitor; a second input coupled to said first pressure sensor; a thirdinput coupled to said first temperature sensor; a first output coupledto said first valve; and, a second output coupled to said flowregulator, wherein said controller is arranged to bleed off excessamounts of said vapor in said first direction of said delivery line byvarying said first output to adjust said valve and by varying saidsecond output to adjust the amount of said inert gas that is supplied tosaid delivery line by said gas source, based upon the measured flow ofsaid vapor at said first input, the measured pressure of said vapor atsaid second input, and the measured temperature of said vapor at saidthird input.
 35. A chemical vapor deposition system comprising: avaporization chamber; a first surface within said vaporization chamber,said first surface arranged to hold a solid precursor material; aheating device arranged to heat said first surface sufficient totransform said solid precursor material to a vapor; a depositionchamber; a delivery line arranged to couple said deposition chamber tosaid vaporization chamber, said delivery line having a first deliveryline arranged to route said vapor in a first direction from saidvaporization chamber toward said deposition chamber, and said deliveryline having a second delivery line arranged to route said vapor in asecond direction from said vaporization chamber away from saiddeposition chamber; a first flow monitor arranged to measure the flow ofsaid vapor through said delivery line in said first direction; a firstvalve arranged to regulate the flow of said vapor through said deliveryline in said second direction; a first pump coupled to said deliveryline, said first pump arranged to draw vapor through said delivery linein said second direction; and, a controller having a first input coupledto said first flow monitor and a first output coupled to said firstvalve, said controller arranged to bleed off excess amounts of saidvapor in said first direction of said delivery line by varying saidfirst output to adjust said valve based upon the measured flow of saidvapor at said first input.
 36. A vapor delivery system for a solidprecursor comprising: a vaporization chamber; a first surface withinsaid vaporization chamber, said first surface arranged to hold a solidprecursor material; a heating device having a temperature control, saidtemperature control arranged to vary the temperature of said heatingdevice over a range of temperatures, at least a portion of thetemperatures within said range of temperatures sufficient to transformsaid solid precursor material to a vapor, wherein said heating device isarranged to transfer heat to said first surface; a delivery line coupledto said vaporization chamber, said delivery line arranged to route saidvapor in a first direction and a second direction; a first flow monitorarranged to measure the flow of said vapor through said delivery line insaid first direction; a valve arranged to regulate the flow of saidvapor through said delivery line in said second direction; a first pumpcoupled to said delivery line, said first pump arranged to draw vaporthrough said delivery line in said second direction; a controller havinga first input coupled to said first flow monitor, a first output coupledto said temperature control of said heating device, and a second outputcoupled to said valve, said controller arranged to control the supply ofsaid vapor to said delivery line in said first direction based upon themeasured flow of said vapor at said first input by varying said firstoutput to adjust the temperature of said heating device and to bleed offexcess amounts of said vapor in said first direction by varying saidsecond output to adjust said valve.
 37. A vapor delivery system for asolid precursor according to claim 36, further comprising a pressuresensor arranged to measure the pressure of said vapor within saiddelivery line in said first direction, wherein said controller has asecond input coupled to said pressure sensor, said second inputreceiving as a second input signal the measured pressure of said vapor.38. A vapor delivery system for a solid precursor according to claim 37,wherein said controller is arranged to vary said first output to adjustthe temperature of said heating device based upon the measured pressureof said pressure sensor.
 39. A vapor delivery system for a solidprecursor according to claim 38, wherein said controller is arranged tocompare said measured pressure against a guard band range of pressures,and said controller varies said first output to adjust the temperatureof said heating device if said measured pressure is outside of saidguard band range of pressures.
 40. A vapor delivery system for a solidprecursor according to claim 36, further comprising a temperature sensorarranged to measure the temperature of said vapor within said deliveryline in said first direction, wherein said controller has a second inputcoupled to said temperature sensor, said second input receiving as asecond input signal the measured temperature of said vapor.
 41. A vapordelivery system for a solid precursor according to claim 36, furthercomprising a gas source coupled to an inlet in said vaporizationchamber, wherein said gas source is arranged to supply a gas to saiddelivery line, said gas transferred to said delivery line to regulatethe pressure within said delivery line.
 42. A vapor delivery system fora solid precursor according to claim 41, wherein said controller furthercomprises a second output adapted to adjust the amount of said gas thatis supplied to said delivery line by said gas source.
 43. A vapordelivery system for a solid precursor according to claim 41, whereinsaid gas comprises an inert gas.
 44. A vapor delivery system for a solidprecursor according to claim 36, wherein said first valve comprises adigital valve.
 45. A vapor delivery system for a solid precursoraccording to claim 36, wherein said first valve comprises a pulsed gatevalve.
 46. A vapor delivery system for a solid precursor according toclaim 36, wherein said first valve is positioned upstream of said firstflow monitor.
 47. A vapor delivery system for a solid precursorcomprising: a vaporization chamber; a first surface within saidvaporization chamber, said first surface arranged to hold a solidprecursor material; a heating device having a temperature control, saidtemperature control arranged to vary the temperature of said heatingdevice over a range of temperatures, at least a portion of thetemperatures within said range of temperatures sufficient to transformsaid solid precursor material to a vapor, wherein said heating device isarranged to transfer heat to said first surface; a delivery line coupledto said vaporization chamber, said delivery line arranged to route saidvapor in a first direction and a second direction; a flow monitorarranged to measure the flow of said vapor through said delivery line insaid first direction; a pressure sensor arranged to measure the pressureof said vapor within said delivery line in said first direction; a valvearranged to regulate the flow of said vapor through said delivery linein said second direction; a first pump coupled to said delivery line,said first pump arranged to draw vapor through said delivery line insaid second direction; a gas source coupled to an inlet in saidvaporization chamber, said gas source arranged to supply an inert gas tosaid delivery line; a flow regulator between said gas source and saidinlet in said vaporization chamber; and, a controller having a firstinput coupled to said flow monitor, a second input coupled to saidpressure sensor, a first output coupled to said temperature control ofsaid heating device, a second output coupled to said valve, and a thirdoutput coupled to said flow regulator, said controller arranged tocontrol the supply of said vapor to said delivery line in said firstdirection based upon the measured flow and pressure of said vapor atsaid first and second inputs by varying said first output to adjust thetemperature of said heating device, to bleed off excess amounts of saidvapor in said first direction by varying said second output to adjustsaid valve, and by varying said third output to adjust the amount ofinert gas in said delivery line.
 48. A vapor delivery system for a solidprecursor comprising: a vaporization chamber; a first surface withinsaid vaporization chamber, said first surface arranged to hold a solidprecursor material; a heating device having a temperature control, saidtemperature control arranged to vary the temperature of said heatingdevice over a range of temperatures, at least a portion of thetemperatures within said range of temperatures sufficient to transformsaid solid precursor material to a vapor, wherein said heating device isarranged to transfer heat to said first surface; a delivery line coupledto said vaporization chamber, said delivery line arranged to route saidvapor in a first direction and a second direction; a flow monitorarranged to measure the flow of said vapor through said delivery line insaid first direction; a pressure sensor arranged to measure the pressureof said vapor within said delivery line in said first direction; atemperature sensor arranged to measure the temperature of said vaporwithin said delivery line in said first direction; a valve arranged toregulate the flow of said vapor through said delivery line in saidsecond direction; a first pump coupled to said delivery line, said firstpump arranged to draw vapor through said delivery line in said seconddirection; a gas source coupled to an inlet in said vaporizationchamber, said gas source arranged to supply an inert gas to saiddelivery line; a flow regulator between said gas source and said inletin said vaporization chamber; and, a controller having a first inputcoupled to said flow monitor, a second input coupled to said pressuresensor, a third input coupled to said temperature sensor, a first outputcoupled to said temperature control of said heating device, a secondoutput coupled to said valve, and a third output coupled to said flowregulator, said controller arranged to control the supply of said vaporto said delivery line in said first direction based upon the measuredflow, pressure, and temperature of said vapor at said first, second, andthird inputs by varying said first output to adjust the temperature ofsaid heating device, to bleed off excess amounts of said vapor in saidfirst direction by varying said second output to adjust said valve, andby varying said third output to adjust the amount of inert gas in saiddelivery line.
 49. A feedback system for controlling the vapor flow of asolid precursor comprising: a flow monitor arranged to measure the flowof vapor between a vaporization chamber and a deposition chamber; aheating device arranged to apply a range of temperatures to saidvaporization chamber to adjust the flow of vapor from said vaporizationchamber; and, a controller arranged to adjust the temperature of saidheating device to adjust the vapor flow measured by said flow monitortoward a predetermined vapor flow.
 50. A feedback system for controllingthe vapor flow of a solid precursor according to claim 49, furthercomprising a pressure sensor arranged to measure the pressure of thevapor between said vaporization chamber and said deposition chamber,wherein said controller is arranged to adjust the pressure of the vaporby adjusting the temperature of said heating device if the measuredpressure is outside a guard band range of pressures.
 51. A feedbacksystem for controlling the vapor flow of a solid precursor comprising: aflow monitor arranged to measure the flow of vapor between avaporization chamber and a deposition chamber; a valve positionedupstream of said flow monitor; and, a controller arranged to adjust saidvalve to bleed off portions of the flow of vapor to adjust the vaporflow measured by said flow monitor toward a predetermined vapor flow.52. A feedback system for controlling the vapor flow of a solidprecursor according to claim 51, further comprising a pressure sensorarranged to measure the pressure of the vapor between said vaporizationchamber and said deposition chamber, wherein said controller is arrangedto adjust the pressure of the vapor by adjusting said valve if themeasured pressure is outside a guard band range of pressures.
 53. Afeedback system for controlling the vapor flow of a solid precursorcomprising: a flow monitor arranged to measure the flow of vapor betweena vaporization chamber and a deposition chamber; a heating devicearranged to apply a range of temperatures to said vaporization chamberto adjust the flow of vapor from said vaporization chamber; a valvepositioned upstream of said flow monitor; and, a controller arranged toadjust the temperature of said heating device and adjust said valve tobleed off portions of said vapor flow from said flow monitor to adjustthe vapor flow measured by said flow monitor toward a predeterminedvapor flow.
 54. A feedback system for controlling the vapor flow of asolid precursor according to claim 53, wherein said controller adjustssaid valve if the vapor flow measured by said flow monitor is greaterthan said predetermined vapor flow, and said controller adjusts thetemperature of said heating device within said range of temperatures ifthe vapor flow measured by said flow monitor is less than saidpredetermined vapor flow.
 55. A feedback system for controlling thevapor flow of a solid precursor according to claim 53, wherein saidcontroller adjusts said valve and the temperature of said heating devicesimultaneously if the vapor flow measured by said flow monitor isgreater than said predetermined vapor flow, and said controller adjuststhe temperature of said heating device if the vapor flow measured bysaid flow monitor is less than said predetermined vapor flow.
 56. Afeedback system for controlling the vapor flow of a solid precursoraccording to claim 53, wherein said controller adjusts said valve if thevapor flow measured by said flow monitor is greater than saidpredetermined vapor flow and a fine adjustment is required to adjust thevapor flow measured by said flow monitor toward said predetermined vaporflow, said controller adjusts the temperature of said heating device ifthe vapor flow measured by said flow monitor is greater than saidpredetermined vapor flow and a course adjustment is required to adjustthe vapor flow measured by said flow monitor toward said predeterminedvapor flow, and said controller adjusts the temperature of said heatingdevice if the vapor flow measured by said flow monitor is less than saidpredetermined vapor flow.
 57. A feedback system for controlling thevapor flow of a solid precursor according to claim 53, furthercomprising a pressure sensor arranged to measure the pressure of thevapor between said vaporization chamber and said deposition chamber,wherein said controller is arranged to adjust the pressure of the vaporby adjusting the temperature of the heating device if the measuredpressure is outside a guard band range of pressures.
 58. A feedbacksystem for controlling the vapor flow of a solid precursor according toclaim 53, further comprising a pressure sensor arranged to measure thepressure of the vapor between said vaporization chamber and saiddeposition chamber, wherein said controller is arranged to adjust thepressure of the vapor by adjusting said valve if the measured pressureis outside a guard band range of pressures.